近30年来，河口及毗邻海域的富营养化现象越来越严重，导致这些区域异养微生物的呼吸作用加剧，海水中的溶解有机质会被降解成二氧化碳而释放到大气中去，使得这些区域成为大气二氧化碳的源，认识和理解不同异养微生物对有机质的代谢过程，对于增加河口及毗邻海域的碳汇功能有着重要意义，异养古菌MGII可将河口及毗邻海域区的易降解的溶解有机碳转化为难降解的醚酯类化合物，从而实现储碳的生态功能。本研究以环境变化剧烈的长江口及毗邻区域的异养古菌MGII为研究对象，综合利用分子微生物学、有机地球化学、水化学及脂类生物学等多学科研究方法，解析MGII对有机质的利用类型，并通过实验室培养实验进行验证，以期为微生物生物碳泵（MCP）研究提供一个具体的例证，进而为增加河口区及毗邻海域的储碳功能提供理论依据。

The level of eutrophication in estuary and its adjacent coastal ocean increased significantly in over past 30 years in China. The increasing eutrophication would result the mobilization of DOC. The mobilized DOC would be degraded by those heterotrophic microorganisms, which account for the sources of atmospheric CO2. Understanding the interactions between the heterotrophic microorganisms and DOC is important for sinking the carbon in the estuary and its adjacent coastal ocean. Marine Group II (MGII), which is well known as a heterotrophic archaeon, was abundant in the estuary and its adjacent coastal ocean. MGII could transfer the labial DOC into refractory cell membrane, Glycerol Dialkyl Glycerol Tetraethers (GDGTs), which is a suitable candidate for studying the carbon sinking in the estuary and its adjacent coastal ocean. Our proposal will use the methods in molecular microbiology, organic geochemistry, water chemistry and lipid biochemistry to investigate the DOC selectivity of MGII in the Yangtze estuary and its adjacent East China Sea. Our study will unravel the DOC metabolism of MGII in the nature environment, provide a specific example for the research of Microbial Carbon Pump (MCP) and make progress on increasing the sinking of carbon in the estuary and its adjacent coastal ocean.